Many fuel burner systems, particularly large industrial process types of burners, are manually started and are then monitored by a flame detector and a safety system. Typically these systems are controlled by a unit referred to as a flame safeguard programmer, and once a manual start of the system has been accomplished, the flame safeguard programmer takes over monitoring and safe shutdown of the fuel valve in the event of a loss of flame, or the need to shut down the burner.
The large industrial type burners typically are manually started by the depression of a momentary start switch, and they further include a valve which must be manually operated and latched electromagnetically into an open position. This type of valve is commonly referred to as a "free" handle type of valve and is a very expensive type of unit. Also, it is not uncommon to find installed "free" handled valves blocked open when the holding solenoid fails. This is done by removing the side cover of the mechanism and placing a matchbook, block of wood, etc. in front of the solenoid, thereby entirely defeating the safety aspect of the valve.